· · · ·


Ira Furoris, Eta Sagittarii

Proper NamesSephdar, Ira Furoris
Bayer DesignationEta Sagittarii
Flamsteed NumberNone
HR (BSC)6832
Right Ascension18h 17m 38s
Declination-36° 45' 42"
Distance146 light years
45 parsecs
MagnitudeApparent: +3.1
Absolute: -0.1
Spectral ClassM3.5III red giant
Optimum VisibilityJuly

The bow of the Archer Sagittarius is marked by three stars running southward along the Milky Way: Kaus Borealis, Kaus Media and Kaus Australis. Beyond Kaus Australis at the southern end of the bow, approaching the point where Sagittarius borders Corona Australis, lies the third-magnitude red star named Sephdar. Sephdar takes its name from the Arabic for 'fierce warrior', perhaps because of its red colouring, and its alternative Latin name Ira Furoris has a similar derivation, meaning 'furious anger'.

Imagery provided by Aladin sky atlas

Sephdar is a binary system, with the primary star being a red giant some sixty times the diameter of the Sun. This primary, designated Eta Sagittarii A, shows signs of variability, and is thought to be an irregular or long-period variable. Its companion, Eta Sagittarii B, is a dwarf star of the F-type bright yellow classification. This companion star orbits the primary at a distance of some 165 AU (more than five times the distance of Neptune from the Sun) taking a period of about 1,300 years to complete each orbit.


Related Entries